Certainly, you shouldn't potter around at low revs. The worst thing you can
do is labour the engine. Let it rev freely. You will be able to feel when it
is not happy.

Personally, I just drive normally when running in. Not accelerating hard,
nor labouring it up hills at low revs.

I'll go along with what Steve said.

The facts, as I understand them, are that the odds of rings not
seating are low no matter whether you run a break-in procedure or not.
The reason for break-in procedures is to try to put you on the good
side of the odds.

I know plenty of very amateur engine builders who didn't follow a
break-in procedure and have good engines. I also know an engine
builder with a vast amount of experience who follows a factory
recommended  break-in procedure and he managed to build a 998 smoker
where the rings never sealed.

Moto-man's break-in procedure isn't too different from the factory
recommended methods, he just presents it differently. The key point in
the factory procedure is to vary engine rpm as much as possible and to
avoid running constant moderately high rpm, like a long highway trip.
This seems to be exactly what he accomplishes in the methods he
presents. The factory secondarily says to avoid high rpm. This is the
difference between the two methods. Of course, Moto-man is only
working with engines that have extremely high red-lines so they may be
more tolerant of high revs early in life. It's also possible that many
new bike owner's and car owners think that the way to go easy on an
engine is to run low rpm all the time. This is hard on any engine of
any age.

The Moto-man article has some serious logical flaws. First, he has no
idea why the factory recommends their break-in procedure. I don't know
for sure either but I'd find out before I started recommending an
alternate pubicly. Second, he provides no direct comparison data for
his method vs. the factory method. All he has to do is build two
identical engines run them using the two methods. Measure the
compression and leak down then tear down the engines and look at the
pistons. Cylinder temperature might also yeild useful information.
Third, the comparisons he does make are between known good engines
using his method and know bad engines using the owner's interpretation
of the factory method. As far as I can tell he never tears down a
known good factory engine to compare. Of course, no one is going to
let him tear down their good engine.

Another point is that the article generally compares good blueprinted
engines vs. bad factory engines. Factory engines have a much larger
tolerance in the fit of various components. The factory is willing to
suffer the occasional bad or low power engine in exchange for higher
production rates.

Moto-man's statement that his break-in method is applicable to all 4
stroke engines is based on no data what-so-ever. He is simply guessing
from his assumption about why his method works. I have no doubt that
he has had success with his break-in procedure but it's pretty obvious
that he's made a lot of assumptions as to why it works. It's probably
good to keep in mind that high-reving motorcycle engines have a short
life compared to the average car engine. I seem to remember that
30,000 miles is a lot for a motocycle.

My advice is avoid high rpm, avoid low rpm under load and vary the rpm
often. Whether you choose 500 miles or 1500 miles for a break-in
period is up to you. The first 50 - 100 miles is probably the most
important.

Cheers,

Kelley